The Infestation Hypothesis Season 5, Episode 2 -  Aired September 22, 2011

The Infestation Hypothesis

When Penny takes in furniture she found in the street, germophobe Sheldon is horrified and urges Penny to remove the chair from the building. Amy finds herself caught in the middle of the argument between Sheldon and Penny. Meanwhile, Leonard is still adjusting to his long-distance relationship with Priya and tries to spice things up between them.

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Guest Stars: Aarti Mann as Priya, Brian George as Dr. Koothrappali, Alice Amter as Mrs. Koothrappli

Writers: Bill Prady (Story), Steven Molaro (Story), Maria Ferrari (Story), Chuck Lorre (Teleplay), Jim Reynolds (Teleplay), Steve Holland (Teleplay)

Director: Mark Cendrowski

Viewers: 14.65 million Households Rating: 8.7/14 Adults 18-49 Rating: 5/14

Available on iTunes

Episode Notes

  • The title refers to Sheldon's ultimately valid hypothesis that Penny's chair, which she took in from the street, is infested. 

> Sheldon's Spot

When Penny took in a new chair, Sheldon was initially pleased with the seat. After Penny admitted it came from the street, germaphobe Sheldon begged Penny to remove the chair from the building. Despite Sheldon's best efforts, Penny refused to get rid of the chair, until a rat inside the chair bit Amy in the keister.

> Sheldon's Knock

Sheldon uses his knock six times in this episode, five times on Penny's door and once on Amy's. Once in a daydream as he freaks out about Penny's chair. When Sheldon goes to her apartment to tell her to get rid of the chair, Penny answers the door to three of his knocks with pithy welcomes: "What's up, buttercup?", "What's word, hummingbird?" and "What's the gist, physicist?" After Shledon knocks on Amy's doors, she tells him his ritualistic knock is symptomatic of obsessive compulsive disorder, which Sheldon rejects.

Episode Quotes

Amy: You are aware that your ritualistic knocking behavior is symptomatic of obsessive-compulsive disorder?
Sheldon: Is not. Is not. Is not.
Amy: Denial. Denial. Denial.

Leonard: Sheldon, you do this all the time! You fixate on some crazy idea then blow it way out of proportion.
Sheldon: Name one time I've ever done that.
Leonard: How about the time you put GPS trackers in your garbage because you thought North Korean spies were stealing your doodles? The chicken nuggets you thought were human nuggets. The mysterious cloud that was following you around town. Or the time you put my shirt on by accident and thought you were growing again.
Sheldon: I said name one. You need to work on your listening skills.

Penny: What's up, buttercup?

Amy: Kiss me where I've never been kissed before?
Sheldon: You mean like Salt Lake City?

Howard: When you say making it work, does that include doing the cyber nasty?
Leonard: What?
Howard: You know, the virtual pickle tickle. The digital bow-chacka-bow-wow.

News Stories

Title Date Posted
CBS Announces Episode 5.02 August 22, 2011

CBS has announced the second episode of the fifth season. The show returns Thursday, September 22nd at 8/7c with two back-to-back episodes, the first of which was announced last week.  Full story


Leonard is having a virtual breakfast date with Priya in India, causing Sheldon to leave the apartment and go to Penny's. As Sheldon and Penny read their magazines like an old married couple, Sheldon compliments Penny on her comfortable new chair. Penny says she found it outside the building by the curb and paid a homeless guy to bring it to the apartment. Sheldon is horrified to find out it's street furniture and instantly starts undressing so he can shower in Penny's apartment. When he reaches the shower he's disturbed to find a wet Band-Aid on the shower floor, so runs out to use his own shower.

At the university, Howard is preparing his lunch with a $175,000 hydraulic thermoforming press. Howard is surprised to learn Leonard's online chats with Priya aren't of a more intimate nature, given the long distance between them. Howard encourages Leonard to spice up their regular chats or risk losing Priya to somebody back in India. Sheldon turns up asking for Leonard to check his head for lice, convinced he's caught something from Penny's chair.

Sheldon visits Penny to tell her to get rid of the chair as it poses a health risk to the building. Penny tells Sheldon she's had the slipcovers dry-cleaned and fumigated. Sheldon finds the chair's strong chemical spell reassuring and sits down, only to find thousands of bugs crawling over him. Sheldon wakes from the daydream and rushes to Penny's apartment to tell her to get rid of the chair. Leonard's in his bed room video chatting with Priya and failing badly at dirty talk. Priya gets Leonard to take of his shirt and just as she's about to return the favor, the video starts buffering. Waiting for the screen to catch up, Leonard tries small talk with Priya.

Sheldon goes to Amy's apartment to convince her to talk to Penny about her chair. Back at Howard's workshop, Leonard has concerns over the long-distance kissing device Howard has procured, which Howard and Raj disturbingly test out together. Amy and Penny are hanging out in her apartment when Amy questions the chair. Penny sees right through the ruse and is disappointed that Amy let Sheldon talk her into this. Amy jumps out of the chair, claiming something bit her in the tushy. When the girls find something moving in the cushion, they run out of the apartment screaming.

Leonard is attempting to video chat with Priya again, and starts talking dirty before Priya has the chance to explain her parents are sitting next to her. Outside the apartment building, Raj and Howard are impressed to find a free chair. They pick the chair up to take to Sheldon and Leonard's apartment so Raj won't have to sit on the floor any more.